MATLAB: Best way to append regression results

for loopMATLABregression

Hi there!

I am running a linear regression in a finite loop.

Each time, it produces coefficient estimates and 95% confidence interval ranges.

I would like to append these regression results on a separate matrix.

What is the best way to do this?

For example, suppose I run:

%%%

for i = 1:3
    N = i; % this is the polynomial degree
    [p,S] = polyfit(x, y, N);
%%%

I would like to store the coefficients stored in p.

For the 3rd-degree, I have 1×4 double as class for p.

So what is the best way to append 1×4 double class variable into a clean matrix?

The main issue I am having is the dimensions not matching, something along the line with…

"Unable to perform assignment because

the size of the left side is 1-by-1

and the size of the right side is

1-by-2."

Please help…!! Thank you!

Best Answer

P = cell(3,1) ; 
for i = 1:3
    N = i; % this is the polynomial degree
    [p,S] = polyfit(x, y, N);
    P{i} = p ; 
%%%

Related Solutions

MATLAB: Every iteration gives me a column vector of non zero elements. How to store them, all the columns, in either a single vector or an array? Attached is the sample code.

The dimensions of what you want to store are varying...use cell instead.

close all; clear; clc;
STORE = cell(2,1);
for k = 1:2
    rows = 4; columns = 3;
    x = randi([0 3],rows,columns);
    store = zeros(rows,columns);
    Xstore = nan(30,2);
    for j = 1:3
        for i = 1:rows
            store(i,j) = x(i,j);
            %Xstore = store(store>0)
            Xstore = nonzeros(store) ;            
            STORE{j,i,k} = Xstore; % This step does not walk, please
        end
    end
end

MATLAB: Polyfit not showing a curve

polyfit only get you the coefficients, you then have to actually evaluate some values to get the curve. An easy alternative is to use the function polyval (https://de.mathworks.com/help/matlab/ref/polyval.html), which will evaluate the given polynom for the given points. The following code should give you the result you would expect:

% store coordinates
x = [5.2 5.5 5.6 5.8];
y = [6.408 16.125 19.816 27.912];
 
% use polyfit to get coefficients of cubic
p = polyfit(x, y, 3);
yfit = polyval(p,x); % Evaluate polynomial coefficients p in values x
scatter(x, y, 'black');
hold on
plot(x,yfit, 'green');

Best Answer

Related Solutions

MATLAB: Every iteration gives me a column vector of non zero elements. How to store them, all the columns, in either a single vector or an array? Attached is the sample code.

MATLAB: Polyfit not showing a curve

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